In general, an air intake control valve including a valve body to open and close a fluid passage is known. Such an air intake control valve is disclosed in, for example, JP2008-144768A, which will be hereinafter referred to as Patent reference 1.
According to a butterfly-valve-type control valve (an air intake control valve) disclosed in Patent reference 1, the air intake control valve includes a frame-shaped body (a frame) formed with an air intake passage (a fluid passage), and a valve (a valve body) supported by the frame-shaped body to rotate between an open position and a closed position to open and close the air intake passage provided at an inner side of the body.
In addition, according to a known configuration of a surge tank for an internal-combustion engine, an inside space portion of the surge tank is divided into two space portions by a partition wall, and the butterfly-valve-type control valve (the air intake control valve) described in Patent reference 1 is provided at an opening portion formed at the partition wall so that a resonance frequency of an air intake system is changed and thus an effective supercharging effect is obtained in a wide engine operation range. In this configuration, the frame-shaped body (the frame) in a state where the valve (the valve body) is attached thereto is fitted into the opening portion penetrating the partition wall of the surge tank-side. In a case where the valve supported by the body rotates to the open position, the two space portions in the surge tank are in fluid communication with each other through the air intake passage (the fluid passage) formed at the inner side of the body. Further, in a case where the valve rotates to the closed position, the air intake passage formed at the inner side of the body is blocked to separate the two space portions from each other.
In the aforementioned known configuration, however, the frame-shaped body is fitted in the opening portion formed at the partition wall and the air intake passage formed at the inner side of the frame-shaped body is opened and closed with the valve. According to this configuration, it is difficult to provide a sufficient cross-sectional area (an opening area) of the air intake passage opened and closed with the valve. In other words, the frame-shaped body is fitted into the opening portion of the partition wall, and accordingly the cross-sectional area of the air intake passage is smaller than an opening area of the opening portion of the partition wall. Therefore, in a case where the valve is opened and the two space portions are in fluid communication with each other, the cross-sectional area of the air intake passage decreases and therefore a pressure loss of the intake air circulating through the air intake passage increases. Consequently, there is such a problem that an amount of the intake air circulating through the air intake passage decreases, and as a result, a sufficient supercharging effect is not obtained.
Thus, a configuration can be considered, in which the valve (the valve body) is attached directly to the surge tank and the opening portion formed at the partition wall of the surge tank is opened and closed by the valve, and accordingly the opening area of the air intake passage when the valve is open is increased.
In the aforementioned configuration where the opening portion (the fluid passage) of the partition wall is opened and closed by the valve (the valve body) attached directly to the surge tank, the surge tank, that is, one surge tank, may be formed in a manner that, for example, plural members including a member to which the valve is mounted are joined to each other by vibration welding. However, the partition wall dividing the internal portion of the surge tank into the two space portions is susceptible to deformation in the process of joining the plural members with each other by the vibration welding. In a case where strain deformation including curvature and/or torsion is generated at a portion (a seal portion) of the partition wall around the valve due to a way of applying load during the vibration welding, the valve (the valve body) is not uniformly or evenly in contact with the seal portion (a seal surface) of the partition wall around the opening portion (the fluid passage) formed at the partition wall. As a result, sealability or a sealing performance decreases.
A need thus exists for an air intake apparatus and a manufacturing method of the air intake apparatus which are not susceptible to the drawback mentioned above.